Field of the Invention
Embodiments of the present invention relate to a source driver and a display apparatus including the same.
Discussion of the Related Art
A source driver may include latches for driving source lines of a display panel and storing data, level shifters for shifting the voltage level of the stored data, digital-to-analog converters (or decoders) for converting the level-shifted data into analog signals, a resistor string (R-string) for providing a plurality of grayscale voltages and output buffers for amplifying and outputting the analog signals to the source lines.
The source driver may restore latch signals or latch enable signals from clock embedded data received from a timing controller and send the restored latch signals or latch enable signals to the latches. When the latch enable signals are input to the latches, the output buffers may receive the grayscale voltages.
The latch enable signals may not be simultaneously transmitted to the latches corresponding to all channels of the source driver. In this case, the latch enable signals may be spread or delayed, and then transmitted to the latches. Thus, the latches may operate at various times or over various time intervals.
Each of the decoders may select any of the plurality of grayscale voltages provided by the resistor string based on or in response to data stored in a corresponding one of the latches. However, since the decoders use a common resistor string, the common resistor string may fluctuate due to a short circuit that may form when the decoders select the grayscale voltages.
As described above, since the latch enable signals are spread over a time interval, the decoders select grayscale voltages over a time interval. As the latch enable signals are spread over time, the common resistor string continues to fluctuate and may not maintain an accurate resistance value.
The source driver may include the decoders, respectively corresponding to the channels, and may include a common connection line for connecting the channels with the common resistor string.
Fluctuation of the resistor string during the latch enable signal spread time may be further delayed by (i) a resistance component of the common connection line and (ii) an increase in time required for the resistor string to reach an accurate resistance value.
Accordingly, the grayscale voltages may be distorted due to fluctuations in the resistor string, the output of which is transmitted to a decoder corresponding to a latch to which the latch enable signal may not yet be transmitted or asserted. Thus, the output buffer may not maintain a current state and may buffer, amplify and/or output the distorted grayscale voltage received from the decoder.